x2 on the PB Blaster. I started using this stuff to breakdown the rust so that i could rebuild a 1966 Barracuda "Barn find" I have one of my old original sewing machine oil cans filled with the stuff now. Works great.
It CAN be harsh on paint to use with caution. I usually just add a drop or two and watch it soak in, 2 to 3 times a day for two to three days usually does it.